The proposed work for the 05 year of this contract is to utilize the dual-directional and the Full Capability Doppler Diagnostic System developed in the 04 year of this grant to determine the extent to which the new objective visualization can separate turbulence from non-obstructing plaques which produces ultrasonic scattering without turbulence. Studies on the separation of grade IV and grade V stenosis from occlusion will be continued to determine sensitivity, specificity, and accuracy of our improved Doppler Diagnostic System. Studies will also be performed in vitro to test the capability of the Infinite Gate Pulsed Doppler in quantitating diameter and volumetric flow.